Energy conserving intermittent motion device and method

ABSTRACT

In an energy conserving intermittent motion device, energy is alternately stored and released by twisting and untwisting a torsion rod to intermittently rotate a driven member, e.g., a feed platen. The torsion rod is twisted and untwisted by selectively restraining and releasing opposite ends thereof through pairs of clutch devices. Frictional losses in the system are compensated for by a servo-controlled variable torque motor which is controlled so as to supply just enough torque to compensate for the frictional losses.

United States Patent Dahl [ 1 June 20, 1972 [54] ENERGY CONSERVINGINTERMITTENT MOTION DEVICE AND METHOD l72| Inventor: David A. Dahl, FortCollins, C010.

[73] Assignee: Teletype Corporation, Skokie, Ill.

[22] Filed: Oct. 30, 1970 21 Appl. No.: 85,502

[52] US. Cl ..226/8, 226/134, 226/156 [51] Int. Cl. ..B65h 17/22 [58]Field ofSearch ..74/84, 1.5, 2; 226/134, 156.8

[56] References Cited UNITED STATES PATENTS 2,934,339 4/1960 Davis ..226/156 Nordin ..74/1.5 Touchman ..226/ 134 Primary Examiner-Richard A.Schacher Attorney-J. L. Landis and R. P. Miller ABSTRACT In an energyconserving intermittent motion device, energy is alternately stored andreleased by twisting and untwisting a torsion rod to intermittentlyrotate a driven member, e.g., a feed platen. The torsion rod is twistedand untwisted by selectively restraining and releasing opposite endsthereof through pairs of clutch devices. Frictional losses in the systemare compensated for by a servo-controlled variable torque motor which iscontrolled so as to supply just enough torque to compensate for thefrictional losses.

14 Claims, 16 Drawing Figures PATENTEDJUHZO I072 3,670,940

SHEET 4 BF 4 l PRINTER SOL P F F F SOL I L I l 59 H99 90 f 6/ I MANUALCONTROL /05 CLOCK PULSE I I /0/ H COMPARATOR CIRCUIT RESET SIGNALGENERATOR ENERGY CONSERVING INTERMI'I'I'ENT MOTION DEVICE AND METHODBACKGROUND OF THE INVENTION This invention relates to anenergy-conserving intermittent motion device and method, and moreparticularly to improved energy-conserving intermittent motion systemsin which stored energy is released from an elastic member to acceleratea mechanism and then recovered in the elastic member to decelerate andstop the mechanism.

PRIOR ART AND TECHNICAL CONSIDERATIONS In many high speed papertransport mechanisms it is desirable to obtain short step times,however, in order to obtain short step times prior art mechanismsusually required the expenditure of significant amounts of energy to notonly initiate the stepping motion but also to stop the motion. Theapplication of this initiating energy is obtained by the use ofrelatively powerful actuators which increase the inertias imparted tocomponent parts such as platens, belts and the like. The resulting rapidacceleration and deceleration or abrupt stops of these componentsresults in wear, noise and vibration; all of which are undesirablemechanical characteristics.

Generally, the prior art mechanisms do not smoothly accelerate anddecelerate the movable components of the system with harmonic motion,but rather they abruptly initiate motion and then abruptly interruptmotion without recovering in a useful way the kinetic energy initiallyreleased.

SUMMARY OF THE INVENTION An object of this invention is to provide a newand improved mechanism and method for conserving energy in anintermittent motion device.

Another object is to provide improved torsion bar drive systems, of thegeneral type disclosed in R. W. Nordin US. Pat. 3,316,769.

In accordance with a preferred embodiment of the invention, potentialenergy is initially stored in an elastic member such as a twistedtorsion rod and then selectively released to rotate a driven member suchas a paper transporting platen. The twisted torsion rod may be connectedto the platen by a transmission device, such as a epicyclic gear train,and is initially held in the twisted position by pairs of clutchesacting on each end of the rod. By releasing one clutch at one end whileholding the clutch at the other end engaged, the torsion rod willuntwist and rotate the platen in a harrnonically accelerating mode;After the torsion rod has completely untwisted it will retwist clue tomomentum transferred from the rotating platen back through the epicyclicgear train to the torsion rod. While transferring momentum back to thetorsion rod the platen will decelerate until it stops. Since there willbe fiictional losses, all of the energy initially imparted to the platenby the torsion rod cannot be returned, therefore an auxiliary energysource, e.g., an electric motor, is used to impart additional torque tothe platen to compensate for these frictional losses. When the torsionrod stops retwisting, the clutches are again rendered effective topreclude untwisting in the opposite direction. When it is desired toagain rotate the platen, one of the clutches on the opposite end of thetorsion rod is released and the cycle repeats itself.

BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of theinvention may be had by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view, partially broken away, illustrating anenergy conserving intermittent motion device which includes a torsionrod arranged to drive a platen of a printer in accordance with theprinciples of the present invention;

FIG. 2A is a partially schematic sectional view looking from the leftend of FIG. I, taken generally along the line 2A--2A of FIG. 1 andillustrating an initial condition where both ends of the twisted torsionrod are restrained from rotation thereby preventing the platen fromrotating;

FIG. 2B is a schematic view similar to FIG. 2A, but showing portions ofthe right end of the apparatus as viewed from the left in FIG. 1;

FIGS. 3A and 3B are views similar to FIGS. 2A and 2B but with the leftend of the torsion rod in FIG. 3A released for rotation while the rightend in FIG. 38 remains restrained from rotation to allow the rod tountwist and thereby accelerate the platen;

FIGS. 4A and 4B show the left end of the torsion rod in FIG. 4Acontinuing to rotate but retwisting and absorbing momentum from theplaten to decelerate the platen, while the right end of the rod in FIG.48 remains restrained from rotation;

FIGS. 5A and 5B show both ends of the tortion rod again restrained as inFIGS. 2A and 28 while the rod is in a twisted state;

FIGS. 6A and 6B show the right end of the torsion rod in FIG. 6Breleased for rotation to again accelerate the platen as the rod untwistswhile the left end of the rod in FIG. 6A is restrained from rotation;

FIGS. 7A and 7B show the right end of the torsion rod in FIG. 7Bcontinuing to rotate but retwisting to absorb momentum from the platenand thereby decelerate the platenwhile the left end of the rod in FIG.7A is restrained from rotation;

FIGS. 8A and 8B show both ends of the torsion rod again restrained as inFIGS. 2A and 2B and FIGS. 5A and 58 so as to prevent the platen fromrotating; and

FIG. 9 is a block diagram illustrating a control motor which suppliesadditional rotational energy to the intermittent motion device of FIG. Ito compensate for energy losses incurred while operating the device.

DETAILED DESCRIPTION In the illustrated embodiment of the inventiondisclosed in FIG. 1, there is shown an energy-conserving intermittentmotion device for feeding paper (not shown) in a high-speed teleprinter,or page printing machine. Margin feed holes in opposite edges of thepaper receive two sets of pins 12 on a pair of sprocket wheels 13 and 14which are joined by a tubular member which for purposes of thisillustration is a platen 16. The platen I6 is mounted for rotation on apair of disc bearings 17 and 18 positioned within the opposite ends ofthe platen. In order to locate and maintain the platen 16 on thebearings 17 and 18, a pair of circular flanges 19 and 21 are securedwithin the interior of the platen and abut the inner sides of thebearings. The bearings 17 and 18 are in turn rigidly secured torespective support sleeves 23 and 24 which are welded or otherwiseattached to circular mounting plates 26 and 27 secured to side framepanels 28 and 29 of the printer.

The bearings 17 and 18 each have central bores that form additionalbearing surfaces 31 and 32. Mounted for rotation within the bearingsurface 31 is a first hollow spindle 33. The first spindle 33 is rigidlysecured to a first input bevel gear 36 while a second spindle 34 isrigidly secured to a second input bevel gear 37 which is axially alignedwith and spaced from the first bevel gear. The bevel gears 36 and 37 arein turn meshed with third and fourth bevel gears 38 and 39 which areoutput gears mounted for rotation on stud shafts 41 and 42. The shafts41 and 42 are rigidly secured to the platen 16 and will rotate theplaten 16 if the third and fourth bevel gears 38 and 39 are orbitedabout the longitudinal axis of the platen.

The spindles 33 and 34 are rigidly secured to first cylinders 43 and 44which form rotatable portions of a pair of spring clutches, designatedgenerally by the numerals 46 and 47 respectively. Wrapped around thefirst cylinders 43 and 44 are coil springs 48 and 49 which each havefirst ends anchored in bores formed in second cylinders 51 and 52respectively. The second cylinders 51 and 52 are axially aligned with,but slightly spaced from, the first cylinders 43 and 44, and are fixedto the mounting plates 26 and 27 to form fixed portions of the springclutches 46 and 47 In order to selectively prevent the first cylinders43 and 44 from rotating with respect to the second cylinders 51 and 52the coil spring 48 is initially tensioned so as to be tightly wrappedaround both the first cylinder 43 and the second cylinder 51 of theleft-hand spring clutch 46 while the coil spring 49 is initiallytensioned so as to be tightly wrapped around the first cylinder 44 andsecond cylinder 52 of the right-hand clutch 47. This of course preventsthe spindles 33 and 34, which are rigidly connected to the cylinders 43and 44 from rotating thereby holding the first and second bevel gears 36and 37 stationary. When the first and second bevel gears 36 and 37 areheld stationary, the third and fourth bevel gears 38 and 39 areprevented from rotating and orbiting thereby holding the platen 16stationary.

When it is desired to advance the platen either the spindle 33 or thespindle 34 is released to rotate. This release is attained through theagency of clutch control detents 54 and 56, which project from secondends of the coil springs 48 and 49. (See also FIGS. 2A andv B.) When theclutch detents are pulled leftward by actuators 57 and 58 the coilsprings are slightly uncoiled. The actuators 57 and 58 are associatedwith armatures of electro-magnets 59 and 61 which when energizedslidethe actuators 57 and 58 to the left to release the clutches 46 and 47.

Both the first cylinders 43 and 44 and the second cylinders 51 and 52have aligned longitudinal bores for receiving an elastic torsion bar orrod 63, which when twisted and then released provides the torque torotate the platen 16. The torsion rod 63 is rigidly secured at opposedend sections to the first cylinders 43 and 44 of the spring clutches 46and 47 by pins 64 which pass through the torsion rod and are seatedwithin bores 65 in the first cylinders. With this arrangement, thespring clutches 46 and 47 constitute means for selectively clampingthe'end of the torsion rod to retain an axial twist placed in the rod,until rotation of the platen is desired.

The ends of the torsion rod.63 are selectively permitted to rotate,after release of one of the spring clutches 46 or 47, in only theclockwise direction (when looking from the lefl in FIG. 1 and as viewedin FIGS. 2A through 8B) by a pair of one-way clutches designatedgenerally by the numerals 66 and 67. Each of the one-way clutches 66 and67 consists of a pair of shortarcuate slots 68 and 69 (see also FIGS. 2Aand B) which are located in the cylinders 51 and 52 and contain a pairof balls 71 and 72 positioned adjacentto the torsion rod 63. The slots68 and 69 taper counterclockwise toward the torsion rod 63 so that as anend of the rod 63 is rotating in a clockwise direction, the balls 71 and72 will be urged into wider portions of the slots and will allow thetorsion rod to rotate; but, if the end of the torsion rod 63 attempts torotate in the counterclockwise direction, the balls 71 and 72 will becarnmed into narrow portions of the slots and will press against thetorsion rod to prevent it from rotating in the counterclockwisedirection. By preventing alternate ends of the torsion rod 63 fromrotating, the rod may be retained in a twisted condition.

Recalling that the second cylinder 51 is fixed to the side plate it willbe appreciated that, when the coil spring 48 of of the left-hand springclutch 46 is tightened around the first and second cylinders 43 and 51,both the left end of the torsion rod 63 and the first bevel gear 36 areheld stationary. If the spring 49 of the right-hand spring clutch 47 isslack, the cylinder 44 will be free to rotate in the clockwise direction(looking in from the left end) thereby allowing the bevel gear 37 andthe right-hand end of the torsion rod 63 to rotate in the clockwisedirection. When the left-hand spring clutch 46 is locked and theright-hand spring clutch 47 is released, the torsion rod 63 may then belongitudinally twisted a desired amount clockwiseabout its left end byrotating the platen 16 in the clockwise direction. After the torsion rod63 has been twisted by rotating the platen 16 several degrees (forexample I in a typical embodiment) or the equivalent of one half a linespace of paper feed, the spring clutch 47 is engaged and the torsion rodis held in the twisted position by the spring clutch 47 and the one-wayball clutch 67 which prevents counterclockwise rotation of the right endof the torsion rod. While in the twisted condition potential energy isstored in the torsion rod 63, generally as disclosed in the Nordinpatent, and the bevel gear 37 is held stationary. This is the initialposition illustrated in FIGS. 2A and B, where the right end (FIG. 2B) isshown in an exaggerated example twisted 45 clockwise from the left end(FIG. 2A).

If the left-hand spring clutch 46 is then released while the right-handspring clutch 47 is engaged and the torsion rod 63 is twisted with theclockwise twist, the torsion rod will untwist about the right-hand endrotating the cylinder 43, spindle 33 and bevel gear 36 in a clockwisedirection. This is the position illustrated by the arrows in FIG. 1. Thebevel gear 36 will in turn rotate the bevel gears 38 and 39 asillustrated by the arrows, which will react against the stationary bevelgear 37 and orbit about the longitudinal axis of the platen 16. Sincethe gears 38 and 39 are connected to the platen 16 by the shafts 41 and42, the platen angularly accelerates in the clockwise direction, with avery high initial acceleration generally as disclosed in the Nordinpatent, as the gears orbit.

The platen 16 continues to accelerate, but at a progressively decreasingrate of acceleration, under the influence of the untwisting torsion rod63 until the torsion rod is completely untwisted (FIGS. 3A and 3B).Thereafter, the platen continues to rotate due to its momentum andretwists the torsion rod in the reverse direction (with acounterclockwise twist as indicated in FIGS. 4A and 4B) about'itsright-hand end which is clamped by the engaged spring clutch 47. In theretwisting process, the platen decelerates as described in the Nordinpatent, and after the torsion'rod 63 has absorbed all of the momentumtransferred back to it, the torsion rod will stop retwisting and attemptto untwist. However, the one-way clutch 66 will prevent the torsion rod63 from untwisting since the balls 71 and 72 will be cammed against thetorsion rod 63 by the slots 68 and 69 when the lefi end of the torsionrod attempts to rotate in the counterclockwise direction. .Thus, theretwist of the torsion rod is preserved for use in a subsequentadvancing step.

. Since there are frictional forces present in this system, as in anysystem, the torsion rod 63 will not retwist to the extent that it wasoriginally twisted and therefore will tend to store less potentialenergy than it initially had. In order to compensate for thesefrictional losses a servo-controlled variable torque motor 83 isprovided to apply additional torqueto the platen 16 through a belt 84which is positioned in a groove 86 formed in the right end section ofthe platen 16. The motor 83 is controlled by an energy compensatingcircuit which is designated generally by the numeral 87 composed ofgenerally conventional components.

Referring now to FIG. 9 where the servo motor control circuit 87 isshown in detail, a line feed signal is locally generated or received bythe printer when it is desired to rotate the platen 16 to advance thepaper associated therewith. The line feed signal is applied to aflip-flop circuit 88 which alternately channels the signal through oneof a pair of bistable multivibrators or flip-flops 89 and 90 to eitherthe left-hand solenoid 59 or the right-hand solenoid 61 to alternatelyrelease either the left-hand spring clutch 46 or the right-hand springclutch 47 allowing the twisted torsion rod 63 to untwist and rotate theplaten 16. The line feed signal is also received by a clock pulsegenerator 91 which after a predetermined time interval T, generates aclock pulse 92 as shown schematically in the time-pulse diagram 93.

The clock pulse 92 is compared in a comparator circuit 94 to a sensedpulse 95 which is shown schematically in the time pulse diagram 96. Thesensed pulse 95 is generated by a signal generator 97 which is connectedto a magnetic pickup head 98 having a gap 99 that senses the position ofindividual iron slugs 100 which are embedded in the periphery of theplaten 16.

The slugs 100 are separated from one another by a distance whichcorresponds to a single line feed spacing on the paper which is beingprinted upon. While the paper is being printed upon, the platen 16 ispositioned so that the gap 99 of the pickup head 98 is located midwaybetween a pair of the slugs 100. When the paper is advanced a singleline feed spacing the gap 99 is positioned midway between a pair of theslugs 100.

When either of the spring clutches 46 or 47 is released, the platen 16rotates carrying one of the slugs 100 past the gap 99 in the magneticpickup head 98 disturbing the magnetic field in pickup head andgenerating the sensed pulse 95. A time interval T between the initiationof rotation of the platen l6 and the generation of the pulse 95 iscompared in the comparator circuit 94 to the predetermined time intervalT of the clock pulse 92 to generate an output energy pulse 101 which isshown in the diagram 102. The energy pulse 101 is transmitted to themotor 83 through an amplifier I03 and supplies enough energy to themotor while the platen l6 decelerates, to com-- pensate for frictionallosses in the system.

The magnitude of the output pulse 101 is determined by the time relationof the clock pulse 92 with respect to the sensed pulse 95. If the pulses92 and 95 occur at the same time, making T equal to T the comparatorcircuit controls the generation of a pulse having a predetermined amountof energy 101 which energy pulse is applied to the motor 83 so as tosupplement the energy released by the torsion rod 63 to rotate theplaten 16 just enough to provide a single line feed. However, if asensed pulse 95' occurs later than the clock pulse 92 making T greaterthan T indicating that the platen 16 has not rotated either fast enoughor far enough for the predetermined amount of energy to fully compensatefor frictional losses, an amount of energy 101' which is correspondinglygreater than the predetermined amount of energy 101 is applied to themotor 83. On the other hand if a sensed pulse 95" occurs before theclock pulse 92, making T less than T and indicating that the platen 16is rotating too fast or has rotated too far, an amount of energy 101"which is correspondingly less than the predetermined amount of energy101 is applied to the motor 83 causing the motor to generate lesstorque. Thus, the magnitude of the pulse of energy 101 applied to themotor 83 is inversely proportional to the speed of rotation of theplaten 16, so that the motor 83 delivers to the platen 16 just enoughenergy to compensate for frictional losses in the system and the platenwill always rotate the desired amount which is usually a single linespace.

In order to insure that the platen 16 stops after it has rotated thedesired number of degrees, a reset circuit 104 monitors the output pulse101 from the comparator circuit 94 and detects the trailing extremity ofthe output pulse. Upon sensing the trailing extremity of the outputpulse 101, the reset circuit 104 impresses a reset signal on both of thebistable multivibrators 89 and 90 associated with the solenoids 59 and61. The multivibrator 89 or 90 which was set by the flip-flop 88 toenergize its associated solenoid 59 or 61 is then reset to deenergizeits associated solenoid so that the spring clutch 46 or 47 connectedthereto will return to its engaged state and prevent further twisting ofthe torsion rod 63. When it is desired to again rotate the platen 16 theother one of the spring clutches 46 or 47 is released and the cycle isrepeated.

A manual control device 105 is provided to energize the motor 83 and aselected one of the solenoids 59 or 61 through flip-flop 88 so as topermit rotating the platen 16 to pretwist the torsion rod 63 in eitherdirection, or to adjust or change the amount of twist at any time, aswell as permitting adjustment of the position of the platen.

SEQUENTIAL OPERATION Referring now to FIGS, 2A through 88, the series ofsequential steps of one complete cycle of operation of the motiontransferring mechanism is illustrated with each pair of related views (Aand B) depicting various operating conditions of the spring clutches 46and 47, the one-way clutches 66 and 67, the solenoids 59 and 61 and themotion of the torsion rod 63.

FIGS. 2A and 2B illustrate the initial condition where the left-hand endof the torsion rod 63 is held stationary by the spring clutch 46 (FIG.2A) while the right-hand end of the torsion rod has been pretwistedclockwise about its longitudinal axis to store potential energy and isheld stationary by the spring clutch 47 (FIG. 2B).

A platen feed stepping operation is initiated by energizing the solenoid59 to retract the armature 57, thereby loosening the coil spring 48 anddisengaging the spring clutch 46 to allow the left-hand end of thetorsion rod 63 to rotate in the clockwise direction (FIG. 3A). Since theright-hand end of the torsion rod 63 is restrained from rotation by thespring clutch 47, as shown in FIG. 3B, the torsion rod untwists in theclockwise direction about its stationary right-hand end as its left-handend rotates. As the torsion rod 63 untwists, it rotates the cylinder 43(FIG. 1) by means of the pin 64 to drive the spindle 33 which in turnrotates the first bevel gear 36 in a clockwise direction. Rotation ofthe bevel gear 36 rotates the third and fourth bevel gears 38 and 39respectively, as shown in FIG. 1. The rotating third and fourth bevelgears 38 and 39 walk upon the now stationary second bevel gear 37. Asthe third and fourth bevel gears 38 and 39 rotate and walk on thestationary bevel gear 37 they necessarily orbit around the longitudinalaxis of the platen l6 and harmonically accelerate the platen to rotatein a clockwise direction.

Referring now to FIGS. 4A and 4B, the right-hand portion of the torsionrod 63 is still prevented from rotating by the spring clutch 47 whilethe left-hand portion is now retwisting or rewinding due to the transferof inertia from the rotating platen 16, the bevel gears 36, 38 and 39and the spindle 33 back to the torsion rod. In other words, the momentumof the rotating parts returns to the torsion rod 63 the major portion ofthe kinetic energy expended by the torsion rod while it was untwistingthereby retwisting the torsion rod in the reverse direction to storepotential energy therein. As this energy transfer takes place, theplaten I6 is harmonically decelerated until it stops rotating.

Ideally, the torsion rod 63 recovers and stores all the kinetic energyinitially expended; however, due to frictional losses within the system,all of this energy cannot be restored to the torsion rod, therefore, themotor 83 supplies this additional energy through the belt 84 to theplaten 16. The servocircuit motor control 87 insures that the motor 83supplies only that amount of energy necessary to compensate for thefrictional losses within the system.

After the torsion rod 63 has been reverse twisted and the platen 16 hasstopped rotating, there is a tendency for the torsion rod to unwind inthe counterclockwise direction. However, the balls 71 and 72 of theone-way clutch 66 are (l) urged by the torsion rod 63 into the narrowportion of the slots 68 and 69 and (2) cammed against the fixed cylinder51 preventing the torsion rod from untvvisting. At this time, the resetcircuit 104 operates to deenergize the solenoid 59 to operate the leftspring clutch 46 so as to reclamp the left end of the rod 63. Thecondition shown in FIGS. 5A and 58 then exists where the platen 16 isheld stationary while the torsion rod 63 is in a reverse twistedcondition with potential energy stored therewithin. While the platen 16is in this condition the paper being advanced can be printed upon orotherwise utilized.

Referring now to FIGS. 6A through 88, a similar sequence of operation isrepeated, only this time the left end of the rod 63 is prevented fromrotation by the spring clutch 46 while the right-hand end of the torsionrod is released for rotation by the spring clutch 47. Since the torsionrod 63 is prevented from rotating in a counterclockwise direction itonly rotates in a clockwise direction so that by alternately locking andreleasing opposite ends of the rod it continually rotates the platen 16in the clockwise direction.

In FIGS. 6A and 6B, the right-hand end of the rod 63 is shown rotatingin a clockwise direction and driving the spindle 34 to rotate the secondbevel gear 37. Since the first bevel gear 36 is prevented from rotatingby the engagement of the spring clutch 46, the second bevel gear 37causes the third and fourth bevel gears 38 and 39 to orbit about thelongitudinal axis of the platen 16 to rotate the platen 16 in aclockwise direction. Referring now to FIGS. 7A and 7B, the torsion rod63 is shown retwisting in the same fashion as in FIG. 4A. The torsionrod 63 continues to retwist until it has absorbed all of the kineticenergy released by the momentum of the rotating parts and has receivedadditional kinetic energy from the motor 83 to compensate for frictionallosses. The condition illustrated in FIGS. 8A and 8B is similar to FIGS.2A and 2B in which both ends of the torsion rod 63 are again preventedfrom rotating. The cycle illustrated in FIGS. 2A and 28 through FIGS. 8Aand 88 then repeats itself to intermittently rotate the platen 16 inorder to intermittently advance the sheet of paper.

With this arrangement, wherein the decelerating reverse twist of thetorsion bar is augmented and preserved in each cycle for use in the nextcycle, it will be apparent that extremely fast cycle times can berealized, typically a few milliseconds for platen line-feed of the typeillustrated. Note that, in the Nordin patent, the temporary reversetwist is completely unwound and the torsion bar must be fully rewound inthe first direction since only one end of the bar ever drives the load.

Another significant effect is that the unit automatically stops theplaten or load at the desired spot at the end of each cycle, when thetorsion bar has been fully retwisted and attempts to untwist in theopposite direction. Thus, external stops are eliminated and an extremelyquiet device is realized, in addition to eliminating mechanical stopelements which wear, and associated control circuits. While one specificembodiment of the invention has been described in detail above, it willbe apparent that various modifications may be made from the specificdetails described without departing from the spirit and scope of theinvention. In. particular, while a specific clutch and epicyclicgear-drive arrangement is illustrated, various equivalent mechanismscould be substituted. An important feature of the invention resides inthe use of some mechanical coupling mechanism to selectively connectfirst one end of the torsion bar to the load and then the other, todrive the load in the desiredincremental steps while reverse twistingthe torsion bar during each step as disclosed. One additional form ofdrive which can be used in place of the epicyclic gear train shown is arotary-band diferential (not shown), utilizing bevelled wheels in placeof the gears 36-39, the wheels being coupled by pairs of tensioned metalbands to each other and theplaten 16 so that rotation of either of twoinput wheels corresponding to the gears 36-37 causes revolution of afloating bevel member corresponding to one of the gears 38 or 39 torotate the platen.

What is claimed is: 1. In a device for transmitting intermittent motion;a rotatable member,

an elastic agency for alternately storing and releasing energy .whenwound and unwound respectively about alternate ends thereof, means forholding said elastic agency wound about said alternate ends, means forselectively releasing said holding means, means associated with saidalternate ends of saidelastic agency to restrict rotation of said endsto one direction,

means for transferring kinetic energy from said released elastic agencyto said rotatable member to angularly accelerate said rotatable memberand to transfer momenturn from said rotatable member to said elasticagency to decelerate said rotatable member and rewind said elasticagency to store potential energy therein, and

means rendered effective while said rotatable member decelerates forimparting additional kinetic energy to said rotatable member in anamount that is substantially equal to the differance between thereleased kinetic energy and the kinetic energy remaining in saidrotating rotatable member.

2. The mechanism of claim 1 wherein said means for imparting additionalkinetic energy is a variable torque motor controlled by a circuit whichsupplies to the motor a pulse of energy the magnitude of which isinversely proportional to the speed of rotation of the rotatable member.

3. The device of claim 1 wherein said elastic agency is an elongated rodwhich when wound and unwound is twisted about the longitudinal axisthereof.

4. The device of claim 3 wherein said means for transferring kineticenergy includes:

first and second input means individually secured to said ends of saidelastic rod, and

output means connected to said rotatable member and to said first andsecond input means, said output means being driven by said first inputmeans and reacting against said second input means to rotate saidrotatable member when one of said ends of said elastic rod is unwindingand being driven by said second input means and reacting against saidfirst input means to rotate said rotatable member when the other of saidends of said elastic rod is unwinding.

5. The device of claim 4 wherein said first and second input means areinput bevel gears and wherein said output means is at least one outputbevel gear meshed with both of said input bevel gears.

6. In a harmonic intermittent drive mechanism,

a first clutch device,

a second clutch device,

an elongated member twisted about its longitudinal axis and held by saidfirst and second clutch devices,

means for alternately releasing said first and second clutch devices toallow said member to untwist and then retwist,

a driven member, 7 7

means responsive-tothe untwisting of said member for driving the drivenmember, means responsive to the momentum of the driven member forretwisting said elongated member, and

means controlled by the degree of retwisting of said elongated memberfor further retwisting said elongated member to an extent equal to theamount of original twist.

7. The mechanism of claim 6' wherein said first, clutch device and saidsecond clutch device each consist of both a one-way clutch to restrictrotation of the elongated member to one direction and a selectivelyoperated clutch to selectively hold said elongated member.

8. In a mechanism for advancing a driven member,

a torsion rod,

a pair of clutch devices acting on opposite ends of the torsion rod forholding the rod twisted about its longitudinal axis in a first fashion,

means for selectively releasing one of the clutches to allow the rod tountwist,

means for transferring the untwisting motion of said rod to advance thedriven member,

means rendered effective upon the untwisting of the rod and continuedadvance of the driven member under the influence of momentum forretwisting the rod in a fashion opposite to said first fashion, and

means controlled by the extent of advance of the driven member forfurther advancing the driven member to further retwist said bar in saidsecond fashion until the amount of retwist is equal to the amount oftwist in the first fashion and for rendering said released clutcheffective to hold said rod in said retwisted second fashion.

9. In a mechanism for intermittently line feeding a strip of material,

a pair of clutch devices acting on opposite ends of said torsion rod forholding said torsion rod stationary with respect to said frame andinitially twisted about its longitudinal axis in a first fashion,

means for selectively releasing one of the clutches to allow the rod tountwist by allowing one end of said rod to rotate,

first means for transferring rotation positioned within said tubularplaten and connected both to said tubular platen and to said one end ofsaid rod to (1) transfer rotation from said one end of said rod to saidplaten and to (2) retwist said rod in a second fashion opposite to saidfirst fashion upon untwisting of said rod and continued rotation of saidplaten under the influence of momentum,

means for rendering said one of said clutches effective to hold said rodin said retwisted second fashion,

means for selectively releasing the other of said clutches to allow therod to again untwist to rotate the other end of said rod,

second means for transferring rotation positioned within said tubularplaten and connected both to said tubular platen and to said other endof said rod to (I) transfer rotation from said other end of said rod tosaid platen and to (2) retwist said rod in said first fashion upon theuntwisting of said rod and continued rotation of said platen under theinfluence of momentum,

means for rendering said other of said clutches efiective to hold saidrod in said retwisted first fashion, and

means controlled by the extent of rotation of the platen to furtherretwist said torsion rod when said torsion rod is retwisting until theamount of retwist is equal to the amount of original twist existing ineither the first or second fashions.

10. A mechanism for transmitting intennittent motion to a load, whichcomprises:

a torsion bar;

means for selectively clamping the ends of the bar to retain an axialtwist in the bar;

means for unclamping only a first end of the bar to permit the bar tountwist about the clamped second end, thus rotating the first end of thebar;

means for mechanically coupling the first end of the bar to the load sothat rotation of the first end of the bar drives the load in a desireddirection and so that the momentum of the moving load continues for atime to rotate the first end of the bar after the bar has been untwistedto retwist the bar a given amount in the reverse direction, after whichthe clamping means is actuated to reclamp the first end of the bar toretain the reverse twist;

means for unclamping only the second end of the bar to permit the bar tountwist about the clamped first end, thus rotating the second end of thebar; and

means for mechanically coupling the second end of the bar to the loadsimilarly to the first-end coupling means to drive the load, untwist thebar and retwist it again in the first direction after which the clampingmeans is actuated to reclamp the second end of the bar to retain theretwist.

11. The mechanism as recited in claim 10, further comprising means forapplying additional force to the system while the bar is coupled to theload to further rotate the unclamped end of the bar in the direction itis rotating so as to compensate for the work performed in driving theload and friction losses, to provide a predetermined amount of twistafter each retwisting step.

12. A method of transmitting intennittent motion to a load,

which comprises:

a. twisting a torsion bar about its axis in a first direction;

b. clamping both ends of the bar to retain the twist;

c, unclamping only a first end of the bar to permit the bar to untwistabout the clamped second end, thus rotating the first end of the bar;

d. mechanically coupling the first end of the bar to the load so thatrotation of the first end of the bar drives the load in a desireddirection and so that the momentum of the moving load continues for atime to rotate the first end of the bar after the bar has beenuntwisted, to retwist the bar a given amount in the reverse direction;

e. reclamping the first end of the bar after it has been retwisted adesired amount to retain the reverse twist;

f. subsequently, unclamping only the second end of the bar to permit thebar to untwist about the clamped first end, thus rotating the second endof the bar;

g. mechanically coupling the second end of the bar to the load similarlyto the coupling in step (d) to drive the load, untwist the bar andretwist it again in the first direction; and

h. reclamping the second end of the bar to retain the retwist.

13. The method as recited in claim 12, further comprising the steps ofapplying additional force to the system during steps (d) and (g) tofurther rotate the unclamped end of the bar in the direction it isrotating in steps (c) and (f), so as to compensate for the workperformed in driving the load and for friction losses, to provide apredetermined amount of twist after each ofsteps (d) and (g).

14. In a device for transmitting intermittent motion,

a rotatable member,

an elastic member for alternately storing and releasing energy whenwound and unwound respectively about opposite ends,

means selectively operable to individually prevent rotation of saidopposite ends to allow said elastic member to be alternately wound andunwound about said ends,

means for transferring kinetic energy from said elastic member to saidrotatable member to angularly accelerate said rotatable member wheneither of said ends is unwinding and to transfer momentum from saidrotatable member to said elastic member to decelerate said rotatablemember and rewind said elastic member to store potential energy therein,and

means rendered efiective while said rotatable member decelerates forimparting additional kinetic energy to said rotatable member in anamount substantially equal to the difference between the releasedkinetic energy and the kinetic energy transferred by the momentum ofsaid,

rotating member.

1. In a device for transmitting intermittent motion; a rotatable member,an elastic agency for alternately storing and releasing energy whenwound and unwound respectively about alternate ends thereof, means forholding said elastic agency wound about said alternate ends, means forselectively releasing said holding means, means associated with saidalternate ends of said elastic agency to restrict rotation of said endsto one direction, means for transferring kinetic energy from saidreleased elastic agency to said rotatable member to angularly acceleratesaid rotatable member and to transfer momentum from said rotatablemember to said elastic agency to decelerate said rotatable member andrewind said elastic agency to store potential energy therein, and meansrendered effective while said rotatable member decelerates for impartingadditional kinetic energy to said rotatable member in an amount that issubstantially equal to the difference between the released kineticenergy and the kinetic energy remaining in said rotating rotatablemember.
 2. The mechanism of claim 1 wherein said means for impartingadditional kinetic energy is a variable torque motor controlled by acircuit which supplies to the motor a pulse of energy the magnitude ofwhich is inversely proportional to the speed of rotation of therotatable member.
 3. The device of claim 1 wherein said elastic agencyis an elongated rod which when wound and unwound is twisted about thelongitudinal axis thereof.
 4. The device of claim 3 wherein said meansfor transferring kinetic energy includes: first and second input meansindividually secured to said ends of said elastic rod, and output meansconnected to said rotatable member and to said first and second inputmeans, said output means being driven by said first input means andreacting against said second input means to rotate said rotatable memberwhen one of said ends of said elastic rod is unwinding and being drivenby said second input means and reacting against said first input meansto rotate said rotatable member when the other of said ends of saidelastic rod is unwinding.
 5. The device of claim 4 wherein said firstand second input means are input bevel gears and wherein said outputmeans is at least one output bevel gear meshed with both of said inputbevel gears.
 6. In a harmonic intermittent drive mechanism, a firstclutch device, a second clutch device, an elongated member twisted aboutits longitudinal axis and held by said first and second clutch devices,means for alternately releasing said first and second clutch devices toallow said member to untwist and then retwist, a driven member, meansresponsive to the untwisting of said member for driving the drivenmember, means responsive to the momentum of the driven member forretwisting said elongated member, and means controlled by the degree ofretwisting of said elongated member for further retwisting saidelongated member to an extent equal to the amount of original twist. 7.The mechanism of claim 6 wherein said first clutch device and saidsecond clutch device each consist of both a one-way clutch to restrictrotation of the elongated member to one direction and a selectivelyoperated clutch to selectively hold said elongated member.
 8. In amechanism for advancing a driven member, a torsion rod, a pair of clutchdevices acting on opposite ends of the torsion rod for holding the rodtwisted about its longitudinal axis in a first fashion, means forselectively releasing one of the clutches to allow the rod to untwist,means for transferring the untwisting motion of said rod to advance thedriven member, means rendered effective upon the untwisting of the rodand continued advance of the driven member under the influence ofmomentum for retwisting the rod in a fashion opposite to said firstfashion, and means controlled by the extent of advance of the drivenmember for further advancing the driven member to further retwist saidbar in said second fashion until the amount of retwist is equal to theamount of twist in the first fashion and for rendering said releasedclutch effective to hold said rod in said retwisted second fashion. 9.In a mechanism for intermittently line feeding a strip of material, amounting frame, a tubular platen mounted for rotation with respect tosaid mounting frame to line feed the strip of material, a torsion rodextending longitudinally within said tubular platen, a pair of clutchdevices acting on opposite ends of said torsion rod for holding saidtorsion rod stationary with respect to said frame and initially twistedabout its longitudinal axis in a first fashion, means for selectivelyreleasing one of the clutches to allow the rod to untwist by allowingone end of said rod to rotate, first means for transferring rotationpositioned within said tubular platen and connected both to said tubularplaten and to said one end of said rod to (1) transfer rotation fromsaid one end of said rod to said platen and to (2) retwist said rod in asecond fashion opposite to said first fashion upon untwisting of saidrod and continued rotation of said platen under the influence ofmomentum, means for rendering said one of said clutches effective tohold said rod in said retwisted second fashion, means for selectivelyreleasing the other of said clutches to allow the rod to again untwistto rotate the other end of said rod, second means for transferringrotation positioned within said tubular platen and connected both tosaid tubular platen and to said other end of said rod to (1) transferrotation from said other end of said rod to said platen and to (2)retwist said rod in said first fashion upon the untwisting of said rodand continued rotation of said platen under the influence of momentum,means for rendering said other of said clutches effective to hold saidrod in said retwisted first fashion, and means controlled by the extentof rotation of the platen to further retwist said torsion rod when saidtorsion rod is retwisting until the amount of retwist is equal to theamount of original twist existing in either the first or secondfashions.
 10. A mechanism for transmitting intermittent motion to aload, which comprises: a torsion bar; means for selectively clamping theends of the bar to retain an axial twist in the bar; means forunclamping only a first end of the bar to permit the bar to untwistabout the clamped second end, thus rotating the first end of the bar;means for mechanically coupling the first end of the bar to the loaD sothat rotation of the first end of the bar drives the load in a desireddirection and so that the momentum of the moving load continues for atime to rotate the first end of the bar after the bar has been untwistedto retwist the bar a given amount in the reverse direction, after whichthe clamping means is actuated to reclamp the first end of the bar toretain the reverse twist; means for unclamping only the second end ofthe bar to permit the bar to untwist about the clamped first end, thusrotating the second end of the bar; and means for mechanically couplingthe second end of the bar to the load similarly to the first-endcoupling means to drive the load, untwist the bar and retwist it againin the first direction after which the clamping means is actuated toreclamp the second end of the bar to retain the retwist.
 11. Themechanism as recited in claim 10, further comprising means for applyingadditional force to the system while the bar is coupled to the load tofurther rotate the unclamped end of the bar in the direction it isrotating so as to compensate for the work performed in driving the loadand friction losses, to provide a predetermined amount of twist aftereach retwisting step.
 12. A method of transmitting intermittent motionto a load, which comprises: a. twisting a torsion bar about its axis ina first direction; b. clamping both ends of the bar to retain the twist;c. unclamping only a first end of the bar to permit the bar to untwistabout the clamped second end, thus rotating the first end of the bar; d.mechanically coupling the first end of the bar to the load so thatrotation of the first end of the bar drives the load in a desireddirection and so that the momentum of the moving load continues for atime to rotate the first end of the bar after the bar has beenuntwisted, to retwist the bar a given amount in the reverse direction;e. reclamping the first end of the bar after it has been retwisted adesired amount to retain the reverse twist; f. subsequently, unclampingonly the second end of the bar to permit the bar to untwist about theclamped first end, thus rotating the second end of the bar; g.mechanically coupling the second end of the bar to the load similarly tothe coupling in step (d) to drive the load, untwist the bar and retwistit again in the first direction; and h. reclamping the second end of thebar to retain the retwist.
 13. The method as recited in claim 12,further comprising the steps of applying additional force to the systemduring steps (d) and (g) to further rotate the unclamped end of the barin the direction it is rotating in steps (c) and (f), so as tocompensate for the work performed in driving the load and for frictionlosses, to provide a predetermined amount of twist after each of steps(d) and (g).
 14. In a device for transmitting intermittent motion, arotatable member, an elastic member for alternately storing andreleasing energy when wound and unwound respectively about oppositeends, means selectively operable to individually prevent rotation ofsaid opposite ends to allow said elastic member to be alternately woundand unwound about said ends, means for transferring kinetic energy fromsaid elastic member to said rotatable member to angularly acceleratesaid rotatable member when either of said ends is unwinding and totransfer momentum from said rotatable member to said elastic member todecelerate said rotatable member and rewind said elastic member to storepotential energy therein, and means rendered effective while saidrotatable member decelerates for imparting additional kinetic energy tosaid rotatable member in an amount substantially equal to the differencebetween the released kinetic energy and the kinetic energy transferredby the momentum of said rotating member.